1. Field of the Invention
The invention relates to the field of turbines, internal combustion engines, and aircraft, specifically to helicopters.
2. Description of the Related Art
U.S. Pat. No. 5,454,530 discloses a type of helicopter that is capable of vertical take-offs and landings, the rotor wing may be reconfigured into a hovering state, a turbofan engine with a low bypass ratio is adopted for the drive, and the engine propels the rotors to rotate and the aircraft to fly via production of hot airflow pressure. There are two pipes at jet nozzle of the turbine. One pipe makes a turn toward the flat passages inside the two rotors through a hollow shaft, followed by another turn toward the rotor tips, then directs airflow transversely. The other pipe leads directly to the tail vector or to a multidirectional nozzle, enabling steering and attitude control. When the aircraft reaches a certain altitude and speed, the hot airflow pressure to the rotors is obstructed and the jet flow reverses. Hovering flight is enabled if the rotors rotate at very low speeds. The helicopter made pubic by the US patent document can also be equipped with two drive devices at the roots of each of the two rotors. The lift force is provided by directing the airflow generated by the drive devices transversely after the airflow makes a turn toward the flat passages inside the rotors, followed by another turn to rotor tips. The disadvantages are that only a turbofan engine with a low bypass ratio can be adopted; the hot airflow pressure loses heat, loss of airflow occurs at the corners, and the fuselage imposes aerodynamic drag on the rotors, imposing a thrust loss of 30% in total; due to the high temperature of more than 100° C., the diameter of the rotor is decreased to guarantee reliability. This results in problems such as the rotor area load and a high access fee. The greatest disadvantage of the helicopter made public by U.S. Pat. No. 5,454,530, is that the propeller fan or fan turbine and internal combustion engine are not accepted as drive.
Another US patent (U.S. Pat. No. 6,513,464) discloses a type of two-stroke internal combustion engine that is suitable for installation on the rotor at a distance from the roots. It can directly propel the rotors to rotate, and its advantages are that stratified lean combustion and low discharge can be realized. The disadvantages are the low power-to-weight ratio and the complex structure.